What Are Twins? Dear BeingGirl Experts, I have always been curious about twins. My first question is when a woman is bearing twins, do the babies share one placenta, or do they each have their own? And if they have two placentas, do they get delivered after each baby is born or two at the very end of the delivery? I hope you can answer these questions for me. Thanks, Rebecca --- Dear Rebecca, There are two types of twinning. With identical twins, one egg is fertilized and splits into two fetuses. These twins live in one placenta and share identical DNA. Fraternal twins are created when two eggs are fertilized by different sperm, live in different placentas, and are as related as any brother or sister may be. Twins are usually born one following the other rather quickly, sometimes 10 –15 minutes apart. If they are fraternal, the expected happening is that the placenta of the first will be delivered before the second child is born. I hope this helps you to understand. BeingGirl Experts Wondering what are twins? Get answers from experts at BeingGirl.com.